The Study On The Removal Of Heavy Metal Pollutans From Water By New Adsorption Materials

Nano-MnO2and Graphite oxide are two kinds of cheap and efficient water purification materials,and has good adsorption removal ability on lead, cadmium,mercury and other heavy metal pollutants in water,however,some disadvantages limit their application in water treatment.Nano-MnO2particles are very fine,soluble in water. It is very difficult to separate nano-MnO2particles from the water after the water treatment.It causes the secondary pollution and materials waste;the removal capacity on arsenic in water by graphite oxide is extremely low,and the graphite oxide is water-soluble.The immobilized nano-MnO2and modified graphite oxide are research hot spot and difficult point for removing heavy metals pollutants from water at present,which are very important for popularizing their applications in water treatment.ObjectivesTo prepare the immobilized nanometer manganese dioxide and solve the problem of separating the nanometer manganes dioxide from water solution,the arsenic and mercury removal performance from water by chitosan supported nano-MnO2film were studied.To prepare the sulfydryl modified graphite oxide and improve its ability of absorption removal of arsenic in water.Methods(1) The chitosan supported nano-MnO2film was prepared by solution method,and characterized the morphology and structure by electron microscope, X ray diffraction,then the arsenic and mercury removal performance by chitosan supported nano-MnO2film were studied.(2) The sulfydryl modified graphite oxide was prepared by chemical bonding method, the3-mercaptopropyltrimethoxysilane was the modifying agent.then the arsenic removal performance by sulfydryl modified graphite oxide were studied.Results(1) The adsorption experiment results showed the arsenic removal rate by chitosan supported nano-MnO2was up to98.88%when the initial concentration was4mg/L at the optimal condition which was that pH was2,temperature was25℃.the dosage of adsorbent was4g/L,the maximum adsorption capacity was13.33mg/g.the absorption isotherm was in accord with the Freundlich model and dynamic curve was in accord with pseudo second-order model;the mercury removal rate by chitosan supported nano-MnO2was up to96.82%when the initial concentration was2mg/L at the optimal condition which was that pH was6,temperature was25℃.the dosage of adsorbent was2g/L.the absorption isotherm was in accord with the Langmuir model and the maximum adsorption capacity was92.59mg/g, and the dynamic curve was in accord with pseudo second-order model.(2) The arsenic removal rate from water by sulfydryl modified graphite oxide was obviously improved and the dynamic curve was in accord with pseudo second-order model.the maximum adsorption capacity was24.45mg/g by Langmuir model when the adsorption temperature was45℃,pH was2.Conclusions(1) The nano-MnO2particles successfully were immobilized to chitosan membranes evenly. Chitosan supported nano-MnO2membranes were insoluble in water,and recovered from water easily.The issue of separating nano-MnO2from water was solved;the composite membrane had good effects on removing arsenic and mercury from water.(2) The sulfydryl modified graphite oxide was prepared successfully.the ability of removing arsenic from water was improved significantly,and it was insoluble.so it was separated from water.